| Crane is an important material handling machinery in modern industry,which can save costs and improve work efficiency.It is widely used in industrial production and plays a very important role in heavy industry.However,due to the crane’s metal structure material itself and welding defects,coupled with long-term alternating loads and harsh environments,fatigue crack damage will inevitably occur.However,these early micro-crack damages are usually difficult to find.Once they accumulate to a certain extent,sudden fracture accidents will occur,causing huge losses and adverse effects.Therefore,the research on early crack damage identification of crane metal structures is of great significance.Structural damage will cause changes in physical parameters such as structural stiffness,mass,and damping,and changes in these parameters will inevitably lead to changes in modal parameters such as structural frequency and mode shape.This method of damage identification using structural modal parameter changes is called global damage identification.It is currently a research hotspot in structural damage identification.It has easy signal extraction and high monitoring efficiency.The monitoring process does not affect the normal use of the structure and can be quantified.Performance changes and other advantages.In view of the fact that traditional structural damage detection methods cannot handle global,real-time and quantitative damage identification problems,a crane metal structure damage identification method based on dynamic characteristics is proposed,with the help of an intelligent auxiliary tool that can perform data analysis,that is,the least squares support vector machine,The damage index is combined with the intelligent method to better realize the damage identification of the structure.The main purpose of this paper is to identify the damage of the metal structure of the bridge crane.First,the finite element software is used to establish the finite element model of the bridge crane metal structure,and the dangerous position of the bridge crane’s main girder is set with different working conditions.Then the bridge crane is modal analysis to obtain the modal frequency,and the contour method is used to Cracks in the main girder of the bridge crane were identified.Secondly,the damage is simulated by changing the elastic modulus of the structure,and the element modal strain energy of the bridge crane’s main girder is analyzed.The damage index of the bridge crane’s main girder is identified using the first-order element modal strain energy change rate.Based on the location of the damage,the approximate degree of damage was calculated.Finally,the least squares support vector machine in the support vector machine is selected as the proxy model,the first-order modal strain energy change rate is used as the input characteristic parameter of the proxy model,and the damage degree is the output quantity.The main girder of the bridge crane is different Damage identification analysis and research on various working conditions such as damage location,different damage degree and multiple damage.The results show that the element modal strain energy change rate combined with the damage identification method of least squares support vector machine can accurately identify the damage location and the degree of damage to the main girder of the bridge crane,both single damage and multiple damage,and the method is simple and efficient. |
